When we were on AT&T, we were always having a situation where the phone didn't ring. Then it might be a day or two before we got the voice message. Moved to Verizon and haven't had any problems yet. We are also using the Verizon MiFi for our internet connections.
+1. Verizon is superior in coverage. In OKC, they assumed the very good old Alltel network. In Tulsa, they recently built the whole network from scratch. Only thing is they are not the cheapest.
I had no issues with AT&T, and neither does my wife, except once I got the company phone through Verizon I realized how much better their coverage is. I have traveled all over OK, Kansas, Missouri, Michigan, and southern California, with great receiption, even in the valleys around LA.
Some people state their service is superior to AT&T or Sprint, though I have no complaints about AT&T. I did have some issue with Sprint's billing around 9 years ago.
If I did not have a company phone (meaning, I were paying my own bill), I would probably have a Boost or Virgin (both use Sprint Network) no-contract unlimited plan, with an AT&T Go Phone in the glove box as a spare if I am roaming.